Dactylariosis is a common poultry fungal disease that usually attacks the respiratory system, although other sites may be involved. Dactylariosis is typically caused by Dactylaria gallopava mold, which is a member of the fungus family. Dactylariosis gallopava will proliferate in aerobic environments, particularly with a high humidity and a temperature over about 25.degree. C. Moldy litter, grain and feed, dust and unclean hatching equipment have been associated with dactylariosis outbreaks.
Inhalation of the spores of Dactylaria gallopava appears to be the primary route of exposure, with young chicks and poults being the most susceptible to an infection.
Post-hatch dactylariosis can also be egg borne, with the mold growing inside the egg. Chicks hatching from such eggs have a high disease risk. Further, outbreaks of dactylariosis are common in young birds, usually occurring within 1-3 weeks of age. A mortality rate of 10-50% is usual in an outbreak of dactylariosis.
Symptoms of the dactylariosis disease are: stunting of growth, gasping, rapid respiration rate, lethargy and increased thirst. The affected poultry may also exhibit leg paralysis, incoordination, torticolis and encephalitis. Encephalitis typically causes lesions in the cerebal cerebellar or optic lobes regions of the poultry. The presence of one or more of these symptoms is not conclusive of a dactylariosis infection. Clinical identification of the mold in affected birds is the only positive diagnosis.
As discussed by F. T. W. Jordan in "Poultry Diseases", Bailliere Tindall, 3rd Edition, pages 216-217, at present there is no feasible treatment for dactylariosis. Affected and infected birds normally are destroyed and the environment must be cleaned rigorously and disinfected.
In the past eggs have been disinfected with a number of agents including natamycin (U.S. Pat. No. 3,343,968). Treating eggs with nataymcin is helpful but does not control dactylariosis attributable to post-hatching environmental conditions.
Natamycin is a member of the polyene family of antimycotics. The compound natamycin is a tetraene with a molecular weight of about 666, an empirical formula corresponding generally to C.sub.33 H.sub.47 NO.sub.13, and contains a glycosidically-linked carbohydrate moiety, mycosamine. It has an isoelectric point of pH 6.5. The structure of natamycin typically exists in two configurations: the enol-structure and the keto-structure.
Natamycin is known as an antibiotic in humans which is discussed in Florey, "Analytical Profiles of Drug Substances", Vol. 10, 1981. As reported in "Pharmacology", Natamycin (Pimaricin) by Wolfgang P. Raab, 1972, Georg Thieme Publishers, Stuttgart, pages 18 and 19, yeasts and molds which infect humans usually exhibit susceptibility to natamycin. The disclosure of each of the above publications is hereby incorporated by reference.
It is an object of the present invention to use natamycin for controlling and preventing diseases in poultry associated with the Dactylaria gallopava mold. The environmental characteristics of the sites on humans and poultry, which may be infected by Dactylaria gallopava, are diverse and, accordingly, the effectiveness of natamycin against a poultry infection of Dactylaria gallopava was a surprising discovery. The surprising effectiveness of natamycin against diseases in poultry associated with Dactylaria gallopava is emphasized when considering the anatomical, metabolic, etc. differences between humans and poultry.
It is a specific object of the present invention to prevent and control diseases caused by an infection of Dactylaria gallopava by including natamycin in the litter and/or atmosphere of the poultry husbandry environment.
Although particular emphasis is placed upon controlling and preventing diseases associated the particular strain of Dactylaria gallopava which affects poultry, other avians (e.g., ducks, turkeys, pheasants, etc.) may be effectively treated in accordance with the present invention. In addition the invention may be used to control and prevent diseases caused by molds which are related to Dactylaria gallopava.